In my last column, I explained how the government now might be able to track us by using data generated by our cell phones. In this column, I will discuss another method of tracking - one that has been around far longer, but has gotten little publicity until recently.

This longstanding tracking method - which I will call "printer identification" -- may be just as dangerous to privacy as more newfangled technologies. Below, I discuss safeguards that can minimize privacy concerns.

It is important to remember, moreover, that not only privacy, but also First Amendment concerns play a role here: A large proportion of the papers that go through our printers count as First Amendment-protected speech. And we need to remember that, in a sense, laser printers are the modern form of the printing press.

Printer Identification: Why It Exists and How It Works

The Electronic Frontier Foundation (EFF) noted in a report last month that a certain model of Xerox color laser printer generates a tiny series of dots - invisible to the naked eye -- on all printed pages. The source of the dots is a chip embedded within the printer - one that, it seems, cannot be removed by the user without breaking the machine.

Xerox is not alone: As a 2004 article in PC Magazine revealed, such identification has been in place in many manufacturers' (including Canon's) color printers for nearly two decades, pursuant to a government-requested program devised by the U.S. Secret Service.

Nor is the U.S. alone; PC Magazine reported in a separate article that the Dutch government uses a similar identification system.

With the right illumination and magnification - the EFF suggests "a blue LED light--say, from a key chain laser flashlight" and a magnifying glass, these dots can be seen.

Once decoded (and EFF offers free software that will do just that), the dots contain

a unique serial number for the printer, and also indicate the time and date of the printout.

The serial number can then be matched up with the company's customer records to identify the owner of the printer. Such identifying information exists because distributors often record the name of the purchaser, or a purchaser may register his purchase as part of a warranty registration program. If you buy a printer with a credit or debit card (which is often the case), the distributor or sales agent will have a record of the purchase.

The purpose of the program is to prevent counterfeiting. That's certainly a worthy aim, and high-end color laser printers may be among counterfeiters' favorite tools.

But the government can - and should - both pursue this aim, and protect privacy at the same time.

Privacy and Free Speech Safeguards Are Essential

When companies cooperate with law enforcement, they become agents of the state. The government should have told the public about this program when it began.

And now that the program has been revealed, it ought to more fully explain the extent to which printer tracking is used and for what purpose. Can any government agency access this information, for any reason - even when counterfeiting is plainly not an issue?

Currently, no law restricts this information to counterfeiting investigations alone. In practice, according to Xerox, the Secret Service has only requested information from the company when counterfeiting has been suspected - but there is no guarantee that this will always be the case.

And what about foreign governments? Can this information be shared with them? Imagine a foreign student studying in the U.S., who anonymously protests his government's actions and tries to get attention for them here. Could the student be tracked down and punished when he returns home because the U.S. government provided his government with information allowing them to identify documents as having come from his printer?

Finally, what about non-government entities? What if, for instance, litigants want to employ the dots to aid the authentication of documents, or establish an evidentiary timeline?

According to the EFF, there is also no law "regulating the distribution or reuse of information obtained through the use of marking technologies and customer databases. "

In the future, legislation may be appropriate to regulate how and when companies must divulge customer information to the government; what notice to the customer is appropropriate when they do so; and what can happen to the information, once divulged - including which governments, and private persons, can and cannot get their hands on it. Such legislation would apply in these, and also many other, circumstances.

It appears that with respect to the government printer identification program, rather than going through typical subpoena processes, the government simply asked the companies to cooperate, which included providing customer information.

It thus avoided the kind of contentious disputes that have happened, more recently, when the government has sought customer information from Internet Service Providers (ISPs)--or when it tried to get PC manufacturers to create unique identifiers for each computer, which triggered a tremendous public outcry.

Americans care about their privacy. The answer surely shouldn't be for the government to act secretly, so we don't know it's being infringed.

Rather, it should be that the government gives us notice of privacy-infringing programs, and makes sure that they contain safeguards that will protects our rights to live privately and speak freely.

Congress must act toward this end, as soon as possible - stepping in to prohibit the government from using printer identification information in a way that poses a threat to our privacy or which chills our speech.

Without Safeguards, We May Experience a Chilling Effect on Speech

Without notice and accountability with respect to printer monitoring (and similar surveillance technologies), there may be a chilling effect, for members of the public will rightly be fearful of when and how the government might monitor printing and discourse. They thus may feel they cannot conduct private life, and private discussions, with the freedom that they otherwise would.

Imagine the kinds of speech that might be chilled or deterred:

Individuals often use color laser printers to create political protest signs, organize legal protest activities. The right to speak encompasses a right to associate with like-minded others. What if membership lists are printed on a laser printer, and then faxed? The government could easily find out who sent what, and when.

In some cases, the individuals who engage in this kind of speech may prefer to remain anonymous. And the Supreme Court has indicated that the right to speak includes the right to speak anonymously, in some situations such as political pamphleteering.

Yet we hardly remain anonymous when even our printers are spying on us, at the very moment our thoughts hit the paper, and are ready to be distributed, on paper, to the world.

Anita Ramasastry is an Associate Professor of Law at the University of Washington School of Law in Seattle and a Director of the Shidler Center for Law, Commerce & Technology. She has previously written on business law, cyberlaw, and other legal issues for this site, which contains an archive of her columns.